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[原创]KCTF 2024 第二题 WriteUp
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发表于: 2024-8-16 14:13
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根据代码要求，flag长度为70，形式为flag{...}，中间的64个字符分为两部分，第一部分56个字符用于解数独，第二部分8个字符用于走迷宫
通过文件偏移dump出要求解的9x9数独，0x0F为需要填入的位置，从左到右、从上到下依次填入1-9数字
def is_safe(board, row, col, num):
for x in range(9):
if board[row][x] == num:
return False
if board[x][col] == num:
return False
if board[3 * (row // 3) + x // 3][3 * (col // 3) + x % 3] == num:
return False
return True
def solve_sudoku(board):
for row in range(9):
for col in range(9):
if board[row][col] == 0x0F:
for num in range(1, 10):
if is_safe(board, row, col, num):
board[row][col] = num
if solve_sudoku(board):
return True
board[row][col] = 0x0F
return False
return True
def print_board(board):
for row in board:
print(" ".join(str(val) if val != 0x0F else "." for val in row))
board = [
[0x0F, 0x0F, 0x02, 0x0F, 0x0F, 0x07, 0x0F, 0x0F, 0x0F],
[0x0F, 0x06, 0x0F, 0x09, 0x0F, 0x0F, 0x04, 0x0F, 0x0F],
[0x0F, 0x09, 0x0F, 0x02, 0x05, 0x0F, 0x0F, 0x0F, 0x03],
[0x0F, 0x0F, 0x0F, 0x04, 0x0F, 0x0F, 0x01, 0x0F, 0x0F],
[0x07, 0x03, 0x0F, 0x0F, 0x06, 0x0F, 0x0F, 0x0F, 0x0F],
[0x0F, 0x0F, 0x09, 0x05, 0x03, 0x0F, 0x0F, 0x06, 0x0F],
[0x0F, 0x0F, 0x06, 0x03, 0x04, 0x0F, 0x0F, 0x07, 0x0F],
[0x08, 0x0F, 0x0F, 0x0F, 0x0F, 0x0F, 0x0F, 0x0F, 0x09],
[0x0F, 0x0F, 0x0F, 0x0F, 0x0F, 0x0F, 0x0F, 0x05, 0x0F],
]if solve_sudoku(board):
print_board(board)
else:
print("No solution exists")
def is_safe(board, row, col, num):
for x in range(9):
if board[row][x] == num:
return False
if board[x][col] == num:
return False
if board[3 * (row // 3) + x // 3][3 * (col // 3) + x % 3] == num:
return False
return True
def solve_sudoku(board):
for row in range(9):
for col in range(9):
if board[row][col] == 0x0F:
for num in range(1, 10):
if is_safe(board, row, col, num):
board[row][col] = num
if solve_sudoku(board):
return True
board[row][col] = 0x0F
return False
return True
def print_board(board):
for row in board:
print(" ".join(str(val) if val != 0x0F else "." for val in row))
[招生]科锐逆向工程师培训(2024年11月15日实地，远程教学同时开班, 第51期)
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